1. Field of the Invention
The present invention relates to a photovoltaic device and a method of manufacturing the same, and more particularly, it relates to a photovoltaic device comprising a first conductivity type crystalline silicon region, a second conductivity type first noncrystalline silicon layer and a substantially intrinsic second noncrystalline silicon layer arranged between the crystalline silicon region and the first noncrystalline silicon layer and a method of manufacturing the same.
2. Description of the Background Art
A photovoltaic device comprising a p-type single-crystalline silicon substrate (crystalline silicon region), an n-type amorphous silicon layer (first noncrystalline silicon layer) and a substantially intrinsic i-type amorphous silicon layer (second noncrystalline silicon layer) is known in general, as disclosed in T. H. Wang, E. Iwaniczko, M. R. Page, D. H. Levi, Y. Yan, H. M. Branz and Q. Wang, “Effect of Emitter Deposition Temperature on Surface Passivation in Hot-Wire Chemical Vapor Deposited Silicon Heterojunction Solar Cells”, Thin Solid Films, 501 (2006), pp. 284 to 287, for example.
The aforementioned literature of H. Wang et al. discloses that an epitaxial layer having a corrugated shape is formed on the surface of the p-type single-crystalline silicon substrate on the interface between the p-type single-crystalline silicon substrate and the i-type amorphous silicon layer by epitaxial growth when the i-type amorphous silicon layer is formed on the p-type single-crystalline silicon substrate. This literature also describes that the output characteristic of the photovoltaic device is reduced when this epitaxial layer remarkably grows, due to deterioration of an interfacial characteristic. The aforementioned literature of H. Wang et al. proposes a technique of preventing the p-type single-crystalline silicon substrate from formation of a crystalline silicon layer (epitaxial layer) resulting from epitaxial growth by reducing the substrate temperature when forming the i-type amorphous silicon layer on the p-type single-crystalline silicon substrate, in order to suppress such reduction in the output characteristic of the photovoltaic device. In other words, the i-type amorphous silicon layer is formed on the p-type single-crystalline silicon substrate without formation of an epitaxial layer in the aforementioned structure proposed by T. H. Wang et al.